Automatic ignition control for internal combustion engines



June 21, 193 A. KAZENMAIER AUTOMATIC IGNITION CONTROL FOR INTERNAL COMBUSTION ENGINES Filed Feb. 12, 1931 2 Sheets-Sheet l J A. KAZENMAIER 1,363,357

AUTOMATIO IGNITION CONTROL FOR INTERNAL COMBUSTION ENGINES Patented June 21, 1932 UNITED STATES PATENT OFFICE AUGUST KAZENMAIER, F STU'I'TGART, GERMANY, ASSIGNOR TO ROBERT BOSCH .AKTIENGESELLSCHAFT, OF STUTTGART, GERMANY AUTOMATIC IGNITION CONTROL FOR INTERNAL COMBUSTION ENGINES Application filed February 12, 1931, Serial No. 515,339, and in Germany February 25, 1930.

In internal combustion engines for motor vehicles the degree of advance of the ignition is often adjusted according to the rotational speed of the motor by an automatic centrifugal governor. When starting it is desirable that rate of advance with relation to the increase of speed for the earlier portion of the adjustment, that is about half of the Whole adjustment be rapid whilst the rate of ad- Vance for the remaining adjustment should be slower in relation to the increase of speed.

In known construction it has been endeavoured to obtain this desired progressive adjustment by arranging the centrifugal weights to displace the cam against the force of a spring the resistance of which steadily increased with the increase of the speed of the motor the spring being arranged between the base plate and a point of a member rigidly connected with the cam. The desired object however is not satisfactorily obtained with this mechanism. When the relationships between the centrifugal force and the spring force differ so much from each other that the curve of adjustment with relation to the engine speed rises quickly at the beginning, then its rise remains too steep when the speed of rotation is further increased and the maximum advance of the ignition is obtained long before the highest speed of rotation of the motor is reached but when, on the other hand, it is endeavoured to obtain a gradual rise with a high speed of rotation, the adjustment in creases too slowly at the beginning, i. e. when starting the motor it is not accelerated in the desired manner.

According to the invention the desired progressive rate of adjustment is obtained in that the centrifugal weight consists of two pendulums one of which acts through a short lever arm on a long lever arm of the cam while the other acts through a long lever arm on a short lever arm of the cam.

Four forms of construction of the invention are illustrated by way of example in the accompanying drawings, in which Figure 1 is a partial longitudinal section of a centrifugal governor.

Figure 2 is a plan view of the centrifugal governor in a position of rest.

Figure 3 is a plan View of a centrifugal governor in the operative position.

Figure 4 is a second form of construction in the position of rest.

Figure 5 is a partial longitudinal section of a third form of construction with a pair of centrifugal weights removed.

Figure 6 is a plan view of Figure 5.

Figure 7 is a rear view of the third form of construction with a pair of centrifugal weights removed.

Figure 8 is a plan view of the third form of construction without the cams and without the upper centrifugal weights.

A flange 2 is mounted on the driving shaft 1 and the base plate of the interrupter, on which are mounted two studs 4, 5, is secured to this flange. Two centrifugal weights 6 and 7 can rotate about the studs 4 and 5 which serve as axles of rotation. The centrifugal weight or pendulum 6 has a short arm 8 which presses against a long arm 9 of a disc 11 firmly connected to the interrupter cam 10. The pendulum 7 has a long arm 12 which presses against the short arm 18 of the disc 11. The disc 14 is also rigidly connected to the cam 10. This disc has two arms 15 and .16 which have specially constructed lateral surfaces 19 and 20 for deviating the spiral springs 17 and 18. The springs are arranged between each of the bolts 21, 22 of the base plate and a point 23, 24, of the disc 14. WVhen the cam is being adjusted the springs roll on the arms 15, 16. The cam 10 on the cam sleeve 23, on which the discs 11 and 14 are mounted is rotatable about the extension 26 of the driving shaft. Narrow bearing pads 50 and 51, on which the centrifugal. weights can slide, are pressed into the base plate in order to keep the friction of the centrifugal weights as small as possible.

The centrifugal governor works in the following manner.

At a certain speed of rotation of the driving shaft 1 the pendulums move outwards. The weight 6 then exerts a large turning moment as a result of the relatively large leverage it has on the arm 9 whilst the moment of theweight 7 is small on account of the length of the arm 12 which reduces its leverage on the arm 13. As the action on the arms 15 and 16 of the springs 17 and 18 is small at the commencement of rotation the large moment of the weight 6 can quickly adjust the cam to such an extent when the speed of rotation is increasing that the path of the weight corresponds to the distance up to the bolt 21 acting as a stop. From the moment when the action of the weight 6 ceases the weight 7 with the large transmission must act alone against the force of the two springs which are tensioned more and more with the increasing adjustment. The result of this is that when the motor is accelerated the rate of increase of advance of the ignition from the time when the weight 7 acts alone is suddenly considerably reduced.

The construction according to Fig. 4 differs only from that of Figures 1 to 3 in the arrangement of the return springs. They are here secured to studs 4 and 5 about which the pendulums rotate and to studs 27 and 28 of the disc 11. The method of operation of the apparatus is not therefore fundamentally changed.

In the third form of construction shown in Figures 5 to 8 the centrifugal weights consist of two independent elements arranged in two planes one above the other. Studs 29 and 30 about which each two centrifugal weights 31, 32, and 33, 34 can rotate are provided on the base plate 3. These weights are disposed one above the other on the belts and have distance pieces 35, 36 interposed therebetween. The lower centrifugal weights have long lever arms with which they engage on bolts 37, 38 of the adjusting plate 39. The upper centrifugal weights act with short lever arms on the bolts 40, 41 of the same adjusting plate 39. This plate is rigidly connected to the cam sleeve 25 and is provided with arms 42 and 43 on which act the springs 17 and 18 as in the first example. The centrifugal weights 31 and 33 are carried by balls 44 and 45 which can roll to and fro on the base plate 3 in slots 46 and 47 of the lower weight, which reduces the friction of the weights 31, The method of operation of this construction is fundamentally the same as in the first two examples. The return springs can be arranged here as in Fig. 4.

The adjustment can be influenced to a very great degree by suitably choosing the centrifugal weights, the lengths of the lever and the constants of the spring whereby the centrifugal weights more particularly have different turning moments about the sleeve 23.

I claim:

1. An automatic ignition control for internal. combustion engines comprising an interrupter cam, resilient means tending to restrain said cam from angular displacement and at least two centrifugal weights adapted to urge said cam in one direction of rotation, one of said weights operating on the cam with greater mechanical advantage than the other.

2. An automatic ignition control for internal combustion engines comprising a rotatable base plate, an interrupter cam angularly displaceable relative to said base plate, resilient means tending to restrain said cam from such angular displacement and at least two centrifugal weights adapted to angularly displace said cam relatively to the base plate, one of said weights operating on the cam with greater mechanical advantage than the other.

3. An automatic ignition control for internal combustion engines comprising an interrupter cam, a short arm and a long arm attached to said cam, resilient means tending to restrain said cam from angular displacement and at least two centrifugal weights, a long lever arm on one of said weights, a short lever arm on the other of said Weights, said long lever arm being adapted to engage said short arm of the cam whilst said short lever arm is adapted to engage said long arm of the cam.

4. An automatic ignition control for internal combustion engines comprising a displaceable interrupter cam, a disc connected therewith, a short and a long arm extending from said disc, a second disc connected to said displaceable cam, an arm extending from said second disc, a spring, a base plate, a pair of pendulums mounted thereon, a long arm extending from one of said pendulums and a short arm extending from the other of said pendulums, the short and long arms of said pendulums being adapted to bear upon the long and short arms of said disc respectively and the spring being connected to the cam at one end and to the base plate at the other end and adapted to be displaced by the arm on said second disc upon displacement of the cam.

5. An automatic ignition control for internal combustion engines including an angularly displaceable interrupter cam, and a pair of p-endulums adapted to actuate said cam upon rotation, the turning moment exerted by one pendulum on said cam being greater than that exerted by the other pendulum during rotation.

6. An automatic ignition control for internal combustion engines comprising an interrupter cam, resilient means tending to restrain said cam from angular displacement and at least two centrifugal weights adapted to swing in a direction perpendicular to the rotational axis of said cam and to urge said cam in one direction of rotation, one of said weights operating on the cam with greater mechanical advantage than the other.

7. An automatic ignition control for internal combustion engines comprising a rotatable base plate, an interrupter camangularly displaceable relative to said base plate, resilient means tending to restrain said cam from such angular displacement and at least two centrifugal weights pivoted one above the other on said base plate and adapted to an- 5 gularly displace said cam relatively to the base plate, one of said weights operating on the cam with greater mechanical advantage than the other.

8. An automatic ignition control for internal combustion engines comprising a rotatable base plate, an interrupter cam angularly displaceable relative to said base plate, resilient means tending to restrain said cam from such angular displacement and at least '15 two centrifugal weights pivoted one above the other on said base plate the upper weight resting on balls bearing on the base plate and housed in openings in the lower weight, said weights being adapted to angularly displace said cam relatively to the base plate, one of said weights operating on the cam with greater mechanical advantage than the other.

In testimony whereof I hereunto afiixed my signature.

AUGUST KAZENMAIER. 

